The SNP has been accused of failing to set out how it will continue to pay for tax-funded universal services.
The party was challenged to explain by the end of 2012 how policies such as free NHS prescriptions can be funded over the next decade.
Conservative finance spokesman Gavin Brown called for Finance Secretary John Swinney to publish the details during a heated Holyrood debate on public service provision on October 3.
The issue shot up the political agenda when Labour leader Johann Lamont used a speech one week earlier to criticise a "something for nothing" society, casting into doubt her party's support for free university tuition fees, the council tax freeze and free prescriptions. She has since gone further by suggesting in a speech last month that students should pay a modest contribution towards their education.
The graduate endowment saw students under the previous Labour-Liberal Democrat coalition at Holyrood pay money towards their education after they graduated. It was scrapped by the SNP, describing it as "back end tuition fees".
Mr Brown said the Finance Secretary should be able to set out a 10-year plan so the substantial issues linked to an ageing population and squeezed public finances can be discussed properly.
"It should have been straightforward for John Swinney to present a 10-year plan, especially with him having most of the information to hand," he said. "Scotland is facing a demographic timebomb, yet the SNP seems determined to provide free prescriptions and travel to those who can well afford it. Unfortunately, it is completely unwilling to show how this would be paid for, which can only lead us to the conclusion that it will be funded through vastly increased taxes and borrowing.
"Asking the SNP to provide such details by the end of the year was not an unreasonable request. But needless to say it has failed to do so - we always set the Scottish Government low expectations, and yet again it has delivered in full. Of course we need a debate on the future of universal free services, but I don't think we can have that debate until we have the necessary data."
A Scottish Government spokesman said: "The Scottish Government has delivered a balanced budget in every single year and still protected the council tax freeze, free university education, free prescriptions and bus passes for our oldest citizens. The UK Treasury has not published figures for what Scotland will receive under the current constitutional settlement for the next decade and it is simply not possible for the Scottish Government to publish a budget over this time period without these figures."
SNP MSP Jamie Hepburn said: "This is nonsense from the Tories, and we will be working hard to achieve a Yes vote for independence in the referendum so that Scotland is in charge of all our nation's abundant resources, enabling us to build a strong economy and fair society - in stark contrast to Westminster wanting to waste up to £100 billion on Trident nuclear weapons."